"Segher Boessenkool" <segher@xxxxxxxxxxxxxxxxxxx> writes: >>> I got no diagnostic when compiling it with "-Wall >>> -O2" switches. Is it expected ? >> >> Yes. -O0 implies -fno-strict-aliasing. > > I misread, you asked for -O2. > > The compiler cannot always detect these situations -- if it could, > it could simply always do what the user expects! > > You can try -Wstrict-aliasing=N for different N; levels 1 and 2 > probably work. The N is a tradeoff between false negatives and > false positives; see the manual for what they do exactly. Ok, using levels 1 or 2 gives the diagnostic. -- Francis
